The invention relates to an alkaline sensitive metal cleaning composition, a method for cleaning an alkaline sensitive metal surface, and a washing facility.
Many articles having a surface that requires cleaning contain an alkaline sensitive metal, such as, aluminum or aluminum containing alloys. Such articles can be found in industrial plants, maintenance and repair services, manufacturing facilities, kitchens, and restaurants. Exemplary equipment having a surface containing an alkaline sensitive metals include sinks, cookware, utensils, machine parts, vehicles, tanker trucks, vehicle wheels, work surfaces, tanks, immersion vessels, spray washers, and ultrasonic baths.
Aqueous alkali cleaners are known as effective cleaning agents. However, many alkali cleaners have disadvantages when used on alkaline sensitive metals, such as, aluminum. A problem with using aqueous alkali systems to clean aluminum surfaces is the potential to corrode and/or discolor. While aqueous alkaline cleaning solutions having a high pH are often more corrosive than aqueous alkaline solutions having a relatively low pH, corrosion and discoloration can still be problematic with the more mild solutions.
Various corrosion inhibitors have been used to prevent corrosion of surfaces that come into contact with aqueous alkaline solutions. Exemplary corrosion inhibitors include silicates, such as, sodium silicate. Sodium silicate has a tendency to begin precipitating from aqueous solution at a pH below 11, thus reducing its effectiveness to prevent corrosion of the contacted surfaces when used in aqueous cleaning solutions having a lower pH. Additionally, when silicates are allowed to dry on the surface to be cleaned, films or spots are often formed, which are visible and which are themselves very difficult to remove. The presence of these silicon containing deposits can affect the texture of the cleaned surface, the appearance of the surface, and on cooking or storage surfaces, can affect the taste of the materials that come into contact with the cleaned surfaces.
An alkaline sensitive metal cleaning composition is provided according to the invention. The alkaline sensitive metal cleaning composition includes an alkaline concentrate and a corrosion inhibitor concentrate that can be diluted and combined to provide a use solution that can be used to clean alkaline sensitive metals. The alkaline concentrate includes a source of alkalinity in an amount sufficient to provide a use solution having a pH of at least 10.0, and a first chelant component that exhibits soil removal properties when used at a pH of at least 10.0. The corrosion inhibitor concentrate includes a corrosion inhibitor component for reducing corrosion of alkaline sensitive metals when used in a use solution having a pH of at least 10.0, a second chelant component for stabilizing the corrosion inhibitor in the corrosion inhibitor concentrate when the corrosion inhibitor concentrate is provided at a pH that is less than 8.0, and a surfactant component for providing cleaning properties when used at a pH of at least 10.0. A threshold inhibitor/crystal modifier can be provided in at least one of the alkaline concentrate and the corrosion inhibitor concentrate to stabilize the corrosion inhibitor in a use solution at a pH of at least 10.0. A hydrotrope component can be included in the corrosion inhibitor concentrate to help stabilize the surfactant component. It should be understood that the hydrotrope component can be omitted if it is not needed to stabilize the surfactant component.
A method for cleaning an alkaline sensitive metal surface is provided according to the invention. The method includes steps of forming the use solution from the alkaline concentrate and the corrosion inhibitor concentrate, and applying the use solution to the alkaline sensitive metal for cleaning the metal.
A washing facility is provided according to the invention. The washing facility can be characterized as a vehicle washing facility when it is constructed to wash vehicles. The washing facility includes a first component tank, a second component tank, a mixing vessel, a water feed, and a use solution line. The first component tank is provided for containing the alkaline concentrate. The second component tank is provided for containing the corrosion inhibitor concentrate. The mixing vessel is provided for mixing water, the alkaline concentrate, and the corrosion inhibitor concentrate to provide a use solution. The water feed is provided for conveying water to the mixing vessel for diluting the alkaline concentrate and the corrosion inhibitor concentrate. The use solution line is provided for conveying the use solution from the mixing vessel to a use solution applicator.